The purpose of this project is to continue assess the neuropsychiatric status of HIV-positive individuals who have abused drugs over a long period of their lives. This protocol includes 60 HIV positive participants who do not show any overt signs or symptoms related to AIDS. Data collected from the HIV positive individuals are being compared to seronegative individuals with similar drug history. Preliminary analyses suggest that HIV-positive individuals have greater asymmetry than HIV-negative subjects on EEG and blood flow. The blood flow data are the first such demonstration while the EEG data replicate those of others.